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toxic megacolon
Etiology:
- colitis
- inflammatory bowel disease (ulcerative colitis)
- pseudomembranous colitis (C difficile colitis) [2]
- Cytomegalovirus in AIDS patients [3]
- Salmonella, Shigella, Campylobacter, enterohemorrhagic E coli 0157, Entamoeba
- precipitants
- hypokalemia
- antimotility agents, opiates, anticholinergics, antidepressants
- barium enema
- colonoscopy & bowel preparation
Pathology:
- chemical mediators such as nitric oxide & interleukins may play a pivotal role in the pathogenesis
Clinical manifestations:
- tachycardia
- fever
- hypotension (shock)
- abdominal pain & tenderness
- abdominal distension
- decreased or absent bowel sounds
- bloody diarrhea
Laboratory:
- complete blood count (CBC)
- leukocytosis (neutrophilia)
Special laboratory:
- colonoscopy is contraindicated (increased risk of perforation)
Radiology:
- abdominal X-ray
- colectomy indicated without CT if diagnosis evident [1]
- colonic dilation > 5.5 cm with systemic toxicity [4]
- computed tomography of the abdomen
Complications:
- colonic perforation
- mortality 40% with emergency surgery
Differential diagnosis:
- Hirschsprung disease
- acquired megacolon
- colonic pseudo-obstruction (Ogilvie syndrome)
- diffuse gastrointestinal dysmotility [3]
Management:
- supportive care
- intravenous fluids
- high-dose glucocorticoids
- broad-spectrum antibiotics
- 3rd generation cephalosporin + metronidazole [1]
- treatment of the underlying colitis
- oral vancomycin + intravenous metronidazole for C difficile colitis [1]
- colonic decompression via tube drainage or positional techniques [2]
- surgical consultation
- subtotal colectomy with ileostomy & either Hartmann pouch, sigmoidostomy, or rectostomy (generally procedure of choice) [1,4]
General
megacolon
References
- Medical Knowledge Self Assessment Program (MKSAP) 16, 18, 19.
American College of Physicians, Philadelphia 2012, 2018, 2021.
- Gan SI, Beck PL.
A new look at toxic megacolon: an update and review of
incidence, etiology, pathogenesis, and management.
Am J Gastroenterol. 2003 Nov;98(11):2363-71.
PMID: 14638335
- Skomorochow E, Pico J
NCBI Bookshelf: Toxic Megacolon
https://www.ncbi.nlm.nih.gov/books/NBK547679/
- NEJM Knowledge+ Gastroenterology
- Strong SA
Management of acute colitis and toxic megacolon.
Clin Colon Rectal Surg. 2010 Dec;23(4):274-84.
PMID: 22131898 PMCID: PMC3134807 Free PMC article